Printed indicia for applying to items of clothing, such as T-shirts, sweatshirts, golf shirts, shorts, hats, and the like, as well as other cloth and paper goods, such as banners, posters, bags, flags, and the like, have become very popular over the last 20 years. Boutiques specializing in printing fanciful and textual indicia—such as slogans, college names, sport team names and logos, licensed characters, and the like—on these various media, are commonly seen in shopping malls across the country. The indicia available at these stores can be pre-printed on a substrate and applied with a heated press by operators at such boutiques to any of the aforementioned items purchased by a consumer or, more commonly, they can be screen printed directly onto the items in mass quantities for later retail sale.
Typically, a screen printing machine has at least one station for each color employed. For example, a design incorporating two colors will have at least two printing stations, one for each color. A design employing eight colors will have at least eight stations. Each station generally includes a printing head, which supports a single screen, the ink to be used at that particular station and a mechanism for applying the ink to the textile. Each color is carried by a single screen. The textile to be screened travels from printing station to printing station by one of a number of methods, such as a chain or a rigid arm. The textile is usually carried by a metal pallet, pallet support, flat bed, or platen. Common printing machines include turret, oval and linear type machines. In addition to printing stations, there may also be curing stations to heat and set the inks placed on the textile or substrate.
In both the linear and oval style printing machines, the pallet carrying the textile to be printed upon travels via a chain on a track or rail from station to station. In the turret or carrousel style printing machine, a center section has a plurality of spider arms. Generally, there are two levels of spider arms, namely, an upper level carrying the printing heads and screens or the curing assemblies, and a lower level carrying the pallet with the textile to be printed upon. Either the lower pallet/textile arms rotate with respect to the printing/curing arms or the printing/curing arms rotate relative to the pallet/textile arms. The stationary arms are commonly referred to as “stations.”
The traveling arm moves from station to station. Specifically, each moving arm is indexed and registered at a station, the station's function, be it printing or curing, is performed and the arm moves to the next station.
For clarity, the discussion following will focus on one configuration, that being moveable lower arms supporting the pallets and textiles and stationary upper arms supporting printing heads or curing units, with the lower arms. It is appreciated this configuration can be different, e.g., stationary printing/curing arms and traveling pallet/textile stations. The teachings of this disclosure work well in any of the configurations.
Highly successful carousel/turret machines are manufactured and sold by M&R PRINTING EQUIPMENT, INC. (“M&R”), Glen Ellyn, Ill. and are sold under the CHAMELEON®, GAUNTLET®, TERMINATOR™, CHALLENGER®, and FORMULA® trademarks.
As to the particulars regarding the screen printing process, a stencil screen is typically blocked (called “masked” in the industry) to embody the desired indicia and is then placed over the item to be printed. Ink of one color is then added to the screen surface and flooded onto the indicia by a flood bar of conventional design. The ink may be of any type well-known in the industry for screen printing. After the ink is flooded onto the screen, the ink is squeegeed through the screen interstices onto the item, leaving ink of the desired color where the interstices in the screen are unblocked. The squeegee can be of any type known in the art. The process may be repeated on each item as many as 16 times using different colors and complementing screens to create just the right design effect. Indexing the screens at each printing station makes this multiple color printing possible.
Placement of these items onto the printing surface of a printing machine can be a critical factor in quality control. Placement of a screened image on, for example, a shirt may typically have only a one-eighth inch tolerance or less in any direction. The tolerance for placement on smaller items may be far less. For this reason, items must be placed with exacting precision onto the printing surface of the printing machine.
Furthermore, it is often desirable to apply ink to the arms of a shirt or the legs of a pair of pants or shorts. It is also often desirable to apply ink to only a portion of the garment. Doing so often requires the use of special pallets for supporting the garments. The special pallets have different widths to accommodate the different widths of the garment legs or sleeves to be printed upon. In particular, to print on a sleeve, the pallet, or a portion of the pallet, is inserted into the sleeve opening with the portion to be printed upon facing the ink carrying screen. Similarly, with pants, the pallet or pallet portion is inserted into the leg opening with the portion to be printed upon facing the screen. Because the widths for the legs differ from the widths of sleeves, specific pallets must be used, depending on the job. For example, pallets for supporting pants must be replaced on a machine with pallets for supporting shirts if there is a job changeover on the machine from printing on the leg of a pair of pants to a sleeve of a shirt.
In addition to the above issues associated with the need and constant changing of pallets, there is a particular problem associated with pallets used to print on pant legs and shirt sleeves. When the squeegee applies a downward force on only a portion of the garment, the pallet on which the garment is resting can, and often does, deflect or exhibit a torsion. Specifically, if the totality of the force applied to the textile and pallet is not directly on the imaginary centerline of the pallet (i.e., the imaginary line passing through the center of the carousel, spider arm and pallet), the pallet may deflect or bend slightly towards and away from the printing head. A twisting or torsion occurs due to the countering forces created by the moment of inertia. Regrettably, even the slightest deflection of the pallet relative to the printing head can have a deleterious effect on the final printed product in that the ink being applied may be uneven and/or poorly applied or the image applied may not be in the exact desired location. In short, any deflection during printing by the pallet carrying the textile can affect the quality of the printing thereon.